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Old 5th January 2012, 09:34 AM   #41
Calvin is offline Calvin  Germany
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Hi,

Quote:
But there is a RIGHT way to reproduce something faithfully. If you want to listen to music as close as possible of the way the original artist made it, there is only one correct "way".
This sentence may be objectively true under the premise(!) that the only correct way means: A "totally subjective impression created by the listeners hearing sense". It may also be true under the premise that You invite the artists and let him or her or them originally perform at Your home.

Quote:
(regarding the Jocko). Requires special transistors (hard to find and need matching).
It now becomes very obvious that You talk rubbish about things You seemingly donīt have a clue about. No special parts at all are needed. Simple BC550 work very well here. The level of distortion depends very much on the bias points, the used parts, the chosen voltages and -not-to forget- the percentage of fullscale output signal (mostly -3dB or -6dBfs).

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Nothing in the material world is "unmeasurable".
Ah Yes, and earth is flat and the Titanic unsinkable and Nuclear plants are absolutely and eternally safe. One could lough about Your sentence if You wouldnīt make it a religious belief.

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...you can swamp the opinions of the realists
A realist would have realized in first place, that HiFi is a luxury item and lifestyle hobby which is based on subjective hearing impression alone.
If the hearing impression of A is preferred over B any technical argument against A becomes rather irrelevant (as long as the devices comply with certain safety and law standards).

jauu
Calvin
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Old 5th January 2012, 02:49 PM   #42
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Quote:
Originally Posted by Calvin View Post

A realist would have realized in first place, that HiFi is a luxury item and lifestyle hobby which is based on subjective hearing impression alone.
If the hearing impression of A is preferred over B any technical argument against A becomes rather irrelevant (as long as the devices comply with certain safety and law standards).

jauu
Calvin


Different people perceive sound differently, just as different people see colors differently. Not only that, our hearing perception changes with age and other factors, so what sounded good to us maybe 20 years ago may not sound good to us today.
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Old 5th January 2012, 02:52 PM   #43
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Calvin,
Please use the quote function properly so that we don't have to look back who you are quoting. Thanks.
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Old 5th January 2012, 03:06 PM   #44
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Originally Posted by Calvin View Post
Ah Yes, and earth is flat and the Titanic unsinkable and Nuclear plants are absolutely and eternally safe.
That's not because there where "unmeasurable" it was just because some people made mistakes in interpreting those measurements or they didn't pay at all attention to them (like the fragility of Titanic steel on cold temperatures).
If you perform a measurement to something, you still need human interpretation of that result. It does NOT make that object "unmeasurable".

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Originally Posted by Calvin View Post
Hi,It now becomes very obvious that You talk rubbish about things You seemingly donīt have a clue about. No special parts at all are needed. Simple BC550 work very well here. The level of distortion depends very much on the bias points, the used parts, the chosen voltages and -not-to forget- the percentage of fullscale output signal (mostly -3dB or -6dBfs).
First of all - "talk rubbish" is an insult that does not add anything relevant to your argument.
You have no clue how thing those transistors have to matched and what transistors you HAVE to use in order to achieve any audio performance and stability with that schematic. Sure, it "works" with any transistors, but for some people "works" is not equal with "works well".

Last edited by SoNic_real_one; 5th January 2012 at 03:31 PM.
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Old 5th January 2012, 10:24 PM   #45
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Originally Posted by olmeister View Post
Hey, i'm new to audio electronics in a sense, i'm currently studying I-V Converters for my first DAC which employs a PCM2707 and PCM1704, similar to that of many designs i've seen around here. I know I could buy someone elses PCB and simply solder the components, but I rather build it from scratch.

I've read that negative feedback op-amps are a bad choice (cant remember why), could someone enlighten me on this?
Personally, i'd for the I-V stage, i'd rather use discrete components such as a BJT, zener etc rather than opamps, just because the study of the internals can be done more comprehensively.

What are desired output characteristics of the voltage gain, snr etc?
And what nth order LPF is applicable? The higher the order (from memory), will reduce the gain, but increase the effectiveness of the LPF.

So therefore, i'm gathering the I-V stage should output a voltage gain with proportion to the order of LPF?

I know theres a few ambiguous questions here, but i'm just looking at peoples views, any help / discussion is welcome and appreciated.

Thanks,
Olmeister


I've been playing with current feedback IC's.... very nice, managed to get my CD player sounding almost the same as my reference transport / DAC combo, but I do have another week of my holiday leave, so everything is possible.

Boky
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Old 5th January 2012, 11:59 PM   #46
rtd is offline rtd  France
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Originally Posted by SoNic_real_one View Post
You have no clue how thing those transistors have to matched and what transistors you HAVE to use in order to achieve any audio performance and stability with that schematic. Sure, it "works" with any transistors, but for some people "works" is not equal with "works well".
Did you try, measure and hear any "discrete I/V" design ?
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Old 6th January 2012, 12:05 AM   #47
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Yes, current feedback IC's are good, and the Analog Devices AD811 is a very good part for an I/V converter. Walt Jung wrote about this device in the The Audio Amateur in the '90's. 2500v/s slew rate. I use the 811 with some LC filtering in front of it, to reduce the RF going into it from the 1541.
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Old 6th January 2012, 12:29 AM   #48
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Originally Posted by abraxalito View Post
I've recently tried AD603 with +/- 50mV compliance voltage (32dB gain) on the TDA1543 DAC with pleasing sonic results. It has the bonus of an in-built volume control too.

http://www.analog.com/static/importe...eets/AD603.pdf
Hi, seeing you have played around with this very interesting opamp, have you found out what the input and output internal opamps are? Can you tell me if it only has 8 different level settings, or am I missing something?

Cheers George
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Old 6th January 2012, 12:52 AM   #49
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Yes, 811 has the lowest input impedance as well. With nice reference recordings I get the impression of performers doing their stuff live, in front of me. For example, I can finally tell the combination of plastic / metal guitar strings… “Krushevo”, MA Recordings (M044A)

Boky
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Old 6th January 2012, 01:42 AM   #50
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Hi George,

Quote:
Originally Posted by georgehifi View Post
Hi, seeing you have played around with this very interesting opamp, have you found out what the input and output internal opamps are?
As far as I can work out, there's no input opamp. Input goes to a ladder attenuator, the tap-off point being controlled by a DC voltage. The output opamp appears to be based on either an AD830 or something very similar.

http://www.analog.com/static/importe...eets/AD830.pdf

Quote:
Can you tell me if it only has 8 different level settings, or am I missing something?
I think you're missing something yep Its gain is continuously variable through about 40dB of range, controlled by a DC voltage. I'm using the AD605 as my system volume control nowadays and it works a treat - no zipper noise from the volume control at all. I'm looking forward to making it remoteable in future
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